1. Field of the Invention
The present invention relates to a light emitting element, and more particularly to an all-angle light emitting element capable of dissipating heat generated by an optical chip effectively and providing a 360-degree all-angle light emission.
2. Description of the Related Art
As the industry of light emitting diode (LED) blooms, the LED has become the most popular light emitting element in the field of illumination. However, the LED generates a large quantity of heat during its light emitting process, and if there is no appropriate heat dissipation, the LED will be overheated and cause lower brightness. When the temperature of LED exceeds 100, the LED and its packaging material will deteriorate, thus causing damages to the light emitting chip and shortening the life of the LED.
As we all know, heat is transmitted via conduction, convection and radiation. Conduction is suitable for solid media. In general, metals and ceramics have better thermal conductivity. If the conductive area of an object is large, the thermal conduction effect will be improved. Convection and radiation are suitable for liquid and gas media. Regarding heat convection, heat can be transmitted from a place with a higher temperature to a place with a lower temperature; and regarding heat radiation, heat can be transmitted via electromagnetic waves. The common heat dissipation methods of LED lamps include increasing the heat dissipating area, using a better thermally conductive material, adding heat dissipating blocks, and installing fans. However, these methods still have drawbacks. For example, the installation of additional heat dissipation blocks or fans incurs a higher cost and requires a manufacturing process to assemble the heat dissipation blocks with the LED as a whole, thus increasing the manufacturing time and cost. If the heat dissipating area is increased, the overall size of a design will be restricted and the choice of material will be relatively more difficult while taking the cost into consideration.
In addition, a conventional LED chip adopts a sapphire substrate with a thermal conductivity of approximately 20 W/mK only and thus it has difficulties to dissipate the heat generated by epitaxial layers to the outside quickly, and the LED is usually packaged by wire bonding. As a result, the speed of conducting heat is very slow when compared with the metal substrate or sapphire substrate, so that the heat source will be conducted from the metal and the heat dissipation effect will be poor.
Therefore, it is an urgent and important subject for related manufacturers to provide an all-angle light emitting element having high heat dissipating efficiency for effectively dissipating the heat generated by the LED chips on the transparent substrate without blocking the light emitted from the LED chip in order to obtain a 360-degree all-angle light source.